Described herein is a method for depositing conformal, stoichiometric or non-stoichiometric, silicon nitride film using one or more organoaminosilane precursors. More specifically, described herein are plasma-based processes including, but not limited to, plasma enhanced atomic layer deposition (“PEALD”), plasma enhanced cyclic chemical vapor deposition (“PECCVD”) that are used for depositing silicon nitride films that are in the fabrication of integrated circuit devices.
Low pressure chemical vapor deposition (LPCVD) processes are one of the more widely accepted methods used by semiconductor industry for the deposition of silicon nitride films. Low pressure chemical vapor deposition (LPCVD) using ammonia may require deposition temperatures of greater than 650° C. to obtain reasonable growth rates and uniformities. Higher deposition temperatures are typically employed to provide improved film properties. One of the more common industry methods to grow silicon nitride is through low pressure chemical vapor deposition in a hot wall reactor at temperatures >750° C. using the precursors silane, dichlorosilane, and/or ammonia. However, there are several drawbacks using this method. For example, certain precursors, such as silane are pyrophoric. This may present problems in handling and usage. Also, films deposited from dichlorosilane may contain certain impurities, such as chlorine and ammonium chloride, which are formed as byproducts during the deposition process.
Precursors that are used in depositing silicon nitride films such as BTBAS and chlorosilanes generally deposit the films at temperatures greater than 550° C. The trend of miniaturization of semiconductor devices and low thermal budget requires process temperature lower than 400° C. and higher deposition rate. The temperature, at which the silicon films are deposited, should decrease in order to prevent ion diffusion in the lattice, particularly for those substrates comprising metallization layers and on many Group III-V and II-VI devices.
US Publ. No. 2013/183835 (“the '835 Publication”) describes methods and apparatus for forming conformal silicon nitride films at low temperatures on a substrate. The methods of forming a silicon nitride layer include performing a deposition cycle including flowing a processing gas mixture into a processing chamber having a substrate therein, wherein the processing gas mixture comprises precursor gas molecules having labile silicon to nitrogen, silicon to carbon, or nitrogen to carbon bonds, activating the precursor gas at a temperature between about 20° C. to about 480° C. by preferentially breaking labile bonds to provide one or more reaction sites along a precursor gas molecule, forming a precursor material layer on the substrate, wherein the activated precursor gas molecules bond with a surface on the substrate at the one or more reaction sites, and performing a plasma treatment process on the precursor material layer to form a conformal silicon nitride layer. The '835 Publication teaches that the processing gas mixture may further include ammonia, hydrazine, helium, argon, hydrogen, nitrogen, xenon, and helium (see the '835 Publication at [0031]). The '835 further teaches that argon and helium may be less desirable to use in the process gas mixture at higher power (e.g., greater than 1 W/cm2) because it may be too reactive in a plasma state and induce excessive dissociation of the precursor molecule (instead of just assisting in the breakage of labile bonds (id.).
US Publ. No. 2009/075490 (“the '490 Publication”) describes a method of preparing a silicon nitride film comprising introducing a silicon wafer to a reaction chamber; introducing a silicon nitride compound to the reaction chamber; purging the reaction chamber with an inert gas; and introducing a nitrogen-containing co-reactant in gaseous form to the reaction chamber under conditions suitable for the formation of a monomolecular layer of a silicon nitride film on the silicon wafer.
US Publ. No. 2009/155606 (“the '606 Publication”) describes a cyclical method of depositing a silicon nitride film on a substrate. In one embodiment a method includes supplying a chlorosilane to a reactor in which a substrate is processed; supplying a purge gas to the reactor; and providing ammonia plasma to the reactor.
U.S. Pat. No. 6,391,803 (“the '803 patent”) describes an atomic layer deposition method of forming a solid thin film layer containing Si.
U.S. Pat. No. 6,528,430 (“the '430 patent”) describes an ALD method for forming silicon nitride thin films employing Si2Cl6 and NH3, or Si2Cl6 and activated NH3 as reactants. In one embodiment of the method, the NH3 reactant is generated in a remote plasma generator to form a plasma and introduced into the chamber in an Ar carrier gas stream (see '430 patent at col. 4, lines 56-62).
U. S. Publ. No. 2010/0081293 (“the '293 Publication”) describes a method for depositing a silicon nitride which includes introducing a silicon precursor and a radical nitrogen precursor to a deposition chamber. The silicon precursor has a N—“Si—”H bond, N—“Si—”Si bond and/or Si—“Si—”H bond. The radical nitrogen precursor is substantially free from included oxygen. The radical nitrogen precursor is generated outside the deposition chamber. The silicon precursor and the radical nitrogen precursor interact to form the silicon nitride based dielectric layer. The '293 Publication further teaches that the use of radical inert gas precursors that can be generated outside the deposition chamber from a starting material selected from Ne, Ar, Kr, and/or Xe (see '293 Publication at [0027]-[0028] and claim 17). The radical inert precursor can be used for depositing a silicon carbon based dielectric layer or depositing a silicon nitride based dielectric layer in combination with a radical nitrogen precursor selected from N, NH, and NH2 (see id. at claim 4).
U. S. Publ. No. 2012/196048 (“the '048 Publication”) describes a method for forming a thin film by alternating multiple times, respectively, a process of adsorbing a precursor onto a substrate and a process of treating the adsorbed surface using a reactant gas and a plasma, wherein the reactant gas is supplied substantially uniformly over the substrate, and the plasma is pulse-time-modulated and applied in the process of supplying the reactant gas.
The reference entitled “Atomic layer controlled growth of Si3N4 films using sequential surface reactions.” Klaus, et al., Surface Science 418: L14-L19 (1998) describes a method for depositing Si3N4 thin films with atomic layer control on Si(100) substrates using sequential surface chemical reactions. The Si3N4 film growth was accomplished by separating the binary reaction 3SiCl4+4NH3→Si3N4+12HCl into two half-reactions. Successive application of the SiC4 and NH3 half-reactions in an ABAB . . . sequence produced Si3N4 deposition at substrate temperatures between 500 and 900° K and SiCl4 and NH3 reactant pressures of 1-10 Torr.
The reference entitled “Plasma-assisted ALD of Silicon Nitride from BTBAS: Influence of Plasma Exposure and Substrate Temperature” 12th International Conference on Atomic Layer Deposition. San Diego, Calif. Knoops, et al (ALD2013) teaches deposition of Si nitride using BTBAS (bis-aminosilane) with N2 plasma. The deposited film has about 5% O2 and about 5% carbon.
The reference entitled “Disilanyl-amines—Compounds Comprising the Structure Unit Si—Si—N, as Single-Source Precursors for Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) of Silicon Nitride”, Schuh et al., Zeitschrift Für Anorganische and Allgemeine Chemie, 619 (1993), pp. 1347-52 describes potential single-source precursors for PECVD of silicon nitride films wherein the precursors have the structural unit Si—Si—N such as (Et2N)2HSi—SiH3, (Et2N)2HSi—SiH(NEt2)2, (i-Pr)2NH2Si—SiH3 and [(i-Pr)2N]H2Si—SiH2[N(i-Pr)2]. The precursor 1,2-bis(di-i-propylamino)disilane (BIPADS) was used for the PECVD deposition of silicon nitride films. The resulting films from the BIPADS precursor exhibited refractive indices ranging from 1.631-1.814 and had low carbon and very low oxygen contents but high (Si-bound) hydrogen contents.
Accordingly, there is a need in the art to provide a low temperature (e.g., processing temperature of 400° C. or below) method for depositing a conformal, high quality, silicon nitride film wherein the film has one or more of the following characteristics: a density of 2.4 grams per cubic centimeter (g/cc) or greater, a low wet etch rate (as measured in dilute hydrofluoric acid (HF)), and combinations thereof compared to other silicon nitride films using other deposition methods.